Lonchodraco giganteus, Rodrigues & Kellner, 2013

Rodrigues, Taissa & Kellner, Alexander Wilhelm Armin, 2013, Taxonomic review of the Ornithocheirus complex (Pterosauria) from the Cretaceous of England, ZooKeys 308, pp. 1-112 : 15-18

Lonchodraco giganteus comb. n. Fig. 4

Pterodactylus giganteus Bowerbank: Bowerbank 1846: p. 8, fig. 1, 2, 5.

Pterodactylus giganteus Bowerbank: Bowerbank 1848: pl. I, fig. 1.

Pterodactylus conirostris Owen: Owen in Dixon 1850: p. 401, pl. XXXVIII, fig. 4-7

Pterodactylus giganteus Bowerbank: Bowerbank 1851: p. 19

Cimoliornis diomedaeus [sic] (Gervais): Owen 1851b: p. 21

Pterodactylus giganteus Bowerbank: Owen 1851a: p. 91, pl. XXXI, fig. 1-9, 12-13

Ornithochirus [sic](?) giganteus (Bowerbank): Lydekker 1888: p. 12

Lonchodectes giganteus (Bowerbank): Hooley 1914: p. 538

Ornithodesmus(?) giganteus (Bowerbank): Arthaber 1922: p. 20, fig. 10

Ornithocheirus giganteus (Bowerbank): Wellnhofer 1978: p. 57, fig. 28

Lonchodectes giganteus (Bowerbank): Unwin 2001: p. 210

Lectotype.

NHMUK PV 39412, anterior portions of the rostrum and mandible, incomplete scapulocoracoid, proximal ends of the humerus and ulna, and a partial wing phalanx ( Fig. 4A-G ).

Type locality.

Near Maidstone, Burham, Kent, England.

Type horizon.

Chalk Formation (Cenomanian / Turonian).

Diagnosis.

Lonchodraconid pterosaur with the following combination of characters that distinguishes it from other members of the clade (autapomorphies are marked with an asterisk): anterior portion of the premaxillae rounded; anterior portion of the dentaries rounded; divergent alveolar margins of the anterior end of the upper and lower jaws; presence of a premaxillary crest; short, low, blade-like dentary crest*; approximately6 alveoli per 3 cm of jaw margin*.

Description.

Lonchodraco giganteus was briefly described by Bowerbank (1846), and then in more detail by Owen (1851a). The lectotype, NHMUK PV 39412, includes the anterior parts of the rostrum and mandible preserved, and, contra Bowerbank (1846) and subsequent authors ( Wellnhofer 1978; Martill 2011), does not include the anterior portion of the nasoantorbital fenestra because what appears to be the anterior margin of the fenestra is not present on both sides of the specimen and most likely represents breakage. The lectotype of Lonchodraco giganteus is readily distinguishable from pterosaurs from other Cretaceous deposits in Britain. Owen (in Dixon 1850) described it as deep-jawed and cone-beaked. The tips of the jaws are dorsoventrally flattened, and there is no upward curvature of the palate. The alveolar margins of the upper and lower jaw are divergent even in their anterior portions. The premaxilla is tall and triangular in lateral view, indicating the presence of a crest. The crest is not thin as seen in Anhanguera or thick as in Coloborhynchus ( Fastnacht 2001; Rodrigues and Kellner 2008). The mandibular symphysis also has a distinctive crest from that in anhanguerids because it does not start at the tip of the mandible. The crest is blade-like, short, and located medially in the relatively wide symphysis. Unfortunately, incomplete preparation of the specimen precludes more detailed observations of its oral region, including the palatal ridge. The mandibular groove appears to be deep but cannot be accurately measured. The teeth are conical and elongated, smaller than the ones in anhanguerids; similarly, the alveoli are small and oval to round. Lonchodraco giganteus has a shorter mandibular crest and a larger tooth density than Lonchodraco machaerorhynchus and a tall rostrum as opposed to the elongated premaxillae and maxillae in Lonchodraco(?) microdon and 'Ornithocheirus' polyodon .

Remarks.

Lonchodraco giganteus has a complex taxonomic history. The species was named Pterodactylus giganteus by Bowerbank (1846). He referred several specimens to the species, including both cranial and postcranial material. Some of these specimens were found associated (NHMUK PV 39412), whereas others were not found associated but came from the same locality as the associated material; additional material was collected at different localities. It is unclear which specimen was considered the holotype. Bowerbank (1848) described the paleohistology of some bones that he referred to Pterodactylus giganteus , including the cranial material (NHMUK PV 39412; Bowerbank 1848: fig. (1). Owen (in Dixon 1850) proposed a new name, Pterodactylus conirostris , for NHMUK PV 39412, because he argued that the specimen was not gigantic in size and thus deemed the specific epithet giganteus inappropriate. Bowerbank (1851) responded that at the time of the description larger pterosaurs were unknown, that modifications of the names of species based on them being inappropriate would cause much instability, and refused to adopt Pterodactylus conirostris . Bowerbank (1851) cited the Law of Priority of the British Association Code (also known as the Strickland Code, published in 1843), which was approved by a committee that included Owen ( International Commission on Zoological Nomenclature 1999; Dayrat 2010; see also Martill 2010). The Law of Priority stated that the first name of a species should be the one considered valid. Owen (1851a, b) answered Bowerbank that he had understood that the name Pterodactylus giganteus was proposed for a bone from the Chalk Formation that he ( Owen 1842) had previously described as avian. He also pointed out that, among the material described and referred as Pterodactylus giganteus by Bowerbank (1846), there were at least two individuals, of very different size, the smaller one (NHMUK PV 39412) being osteologically mature (based on the fusion between scapula and coracoid), and the other one much larger. Owen (1851a, b) assumed the larger individual to be the one referred as Pterodactylus giganteus and thus designated Pterodactylus conirostris for the cranial material and the bones associated with it. He also brought up several rules of the British Association Code on which he based his designations, including exceptions to the Law of Priority in relation to inappropriate names ( Owen 1851a, b; Dayrat 2010), but finally accepted the name Pterodactylus giganteus for the material ( Owen 1851a). The name Pterodactylus conirostris has never been used since, but the question as to which material was the holotype of Pterodactylus giganteus remained overlooked for several years. Hooley (1914: 538) reviewed the species based only on the cranial material (NHMUK PV 39412). Finally, Wellnhofer (1978: 57), in his review, designated NHMUK PV 39412 as the lectotype of Pterodactylus giganteus , citing only the skull material and not the associated bones. Pterodactylus giganteus Bowerbank, 1846 and Pterodactylus conirostris Owen, 1850 clearly are objective synonyms because they are founded on the same type specimen, and the former binomen has priority over the latter.

Figures

Figure 4. Lonchodraco giganteus comb. n. Lectotype NHMUK PV 39412 (Cenomanian / Turonian, Chalk Formation). A-F articulated anterior parts of the rostrum and mandible A right lateral view B respective line drawing C left lateral view D respective line drawing E anterior view F respective line drawing G associated scapulocoracoid in posterior view. Abbreviations: ch - choanae, cor - coracoid, d - dentary, dcr - dentary crest, m - maxillae, pl - palatine, pm - premaxillae, pmcr - premaxillaery crest, prid - palatal ridge, sca - scapula. Arrows indicate alveoli or teeth. Scale bar = 10 mm. Photos courtesy of The Natural History Museum.